This invention generally relates to a safety circuit or a circuit interrupter which interrupts the delivery of alternating current to an appliance whenever a ground fault occurs in the appliance such as when the appliance is accidently dropped into water. More specifically, a sensor is provided surrounding the electrical components of the appliance so that when the appliance is accidently dropped or immersed into water the sensor conducts electrical current from the electrical components through the water and energizes a relay which disconnects the alternating current from the appliance. A latching circuit is then provided to retain the relay energized and the delivery of alternating current to the appliance interrupted.
It is known that in the past people have placed radios near their swimming pools or bath tub while swimming or taking a bath respectively. Further, many people utilize and place small heaters on the side of their bath tubes or sinks for the purpose of keeping warm while taking a bath or while being in the bathroom. Many other electrical appliances such as fans, de-humidifiers, air filters, hair dryers, hair curlers, razors, and other personal care appliances are also used near bath tubes or other bodies of water. Such use or placement of electrical appliances near such bodies of water has in the past proved to be dangerous because the appliances are often accidently knocked or dropped into the water causing an electrical short circuit which in turn creates an electrical field in the water which can shock and often severly injure people within the water. Further yet, larger electrical appliances such as washers and dryers are often times placed in basements which may flood and thereby, again, create an electrical field in the water which can injure people who come in contact with it. Even with greater public awareness people often times disregard warnings and still place and use electrical appliances near water and in basements which are likely to flood.
One solution to this problem has been to use a ground fault interrupter (GFI) whereby current is interrupted and protection is provided for such accidents. GFI's are now often used in bathrooms and kitchen receptacles and in circuit boxes in many homes. GFI's however, are expensive and on occasions may fail. Further, many older homes wired prior to GFI's coming into general use have absolutely no protection for preventing the accidents mentioned above from occurring.
Another solution to the problem of electrical shock caused by electrical appliances has been to provide electrical ground fault protective circuits which utilize an isolation transformer so as to isolate the ground potential of the appliance and thus prevent a ground fault from occurring. Examples of such uses are shown in U.S. Pat. Nos. 3,436,599, 3,229,163, and 3,242,382. Isolation transformers, however, are bulky and substantially add to the cost of the safety circuit. Furthermore, they do not protect the user totally without failing in conditions such as when the appliance is accidently immersed in water.
Another solution to the problem of electrical shock caused by electrical appliances falling into or being immersed in water has been to incorporate an immersion detection circuit interrupter (IDCI) within the plug of the electrical appliance or within the appliance itself. One such IDCI is disclosed in U.S. Pat. No. 4,464,582. The IDCI disclosed therein, however, utilizes a triac to energize a relay and disconnect the alternating power source from the appliance. This makes the IDCI relatively expensive and impractical to use.
Accordingly, there is a need for providing an inexpensive immersion detector circuit interrupter for use with electrical appliances which are used near bodies of water so as to protect individuals from electrical shock which may occur by the appliances falling within the bodies of water.